The invention relates to an electroluminescent device exhibiting a pattern-wise light-emitting surface when driven,
said electroluminescent device comprising an organic emitter layer having an electroluminescent area, a first electrode layer and a second electrode layer,
said organic emitter layer being disposed between said first and said second electrode layer.
An electroluminescent (EL) device as mentioned in the opening paragraph is disclosed in, for example, the International Patent Application WO 97/06223. The known EL device is an EL device in which the electroluminescence originates from an organic compound, or an organic EL device for short. The known organic EL device comprises a polyphenylenevinylene emitter layer disposed between an indium tin oxide (ITO) and an indium electrode layer. The organic emitter layer comprises electroluminescent areas in accordance with a desired pattern. When driven, the surface of the EL device emits light in accordance with said desired pattern. Alternatively, the electrode layers may be structured according to the desired pattern.
The EL device disclosed in International Patent Application WO 97/06223 is particularly suitable to display icons. An icon is a specific high-resolution image having a fixed shape and color (scheme) which can be switched (partially) on or off. It may take the form of a pictogram, a word like "STOP" or "GO", or a number. Alternatively, it may be an area having a color which is different from the color of the area surrounding it. Icons are a clear and attractive means to convey information and are abundantly used in, for example, segmented display devices where they provide information complementary to the information provided by the segmented display area of the display device.
A disadvantage of the known EL device is that if a group of icons is to be accommodated, a relatively large display area will be required. This is of particular concern in portable applications, such as the display panel of a mobile phone, where display area is at a premium. Also, from the viewpoint of design and/or ergonomy it may be less attractive to have a large part of the display area occupied by a group of icons of which many, due to the nature of the information they are to provide, will be off most of the time.